Louisiana Revised Statutes Tit. 48, § 461.18. Outdoor advertising control extended beyond six hundred sixty feet

A. Control of outdoor advertising signs, displays and devices is extended to signs, displays and devices located beyond six hundred sixty feet of the edge of the right of way of the Federal Aid Interstate or Primary Systems outside of urban areas erected with the purpose of their message being read from the main traveled ways of such systems. Such signs, displays or devices are prohibited, whether or not in commercial or industrial areas, unless they are of a class or type allowed under Sections 461.1 through 461.8 within six hundred sixty feet of the edge of the right of way of such system outside of commercial or industrial areas.

B. The term “erected with the purpose of its message being read from the main traveled way of such system” shall not include a sign lawfully in existence adjacent to a highway not controlled under this section, which sign at a later date becomes visible from the main traveled way of an interstate or federal aid primary highway for which the right of way was acquired subsequent to the erection of the sign provided that such sign is not intended to be read primarily from the controlled highway. The circumstances of the sign's erection, the revenues generated by the sign, or changes in the sign's structure, purpose, or size may be considered in determining from which highway the sign is intended to be primarily read.